Forced air ventilation systems are commonly utilized in houses, offices and industrial buildings to provide a controlled atmosphere at particular locations throughout those units. Different locations within those units have different atmospheric requirements and it often has been a problem to provide selective atmospheres based on the requirements of the particular location.
For example, in the home it may be desirable to provide a source of odorant or deodorant in a bathroom area or the like without substantially affecting the atmosphere in other rooms in the home. Sometimes, residents having certain physical impairments must be provided with controlled atmospheres-for example, atmospheres having high humidity or the presence of a vapor to assist breathing. In industrial units, it is not unusual to have local production of malodors which are more easily controlled at the source before they spread to other areas in the buildings.
Forced air ventilation systems provide certain advantages for atmospheric control systems, such as rapid and complete dispersion of vapors introduced into the atmosphere. However, heretofore, those systems also have been difficult to work with since they are usually operated from a single power source from an air source remote from many of the locations at which ventilation is occuring. The locations most often are supplied from a central air source by appropriate duct-work. Most homes, for example, have the air inlet and powered blower located in the basement or other areas remote from the living quarters. Many industrial buildings have units located on the roofs of the buildings. Simply placing a source of odorant or the like in the air inlet results in exposure to the control substance of the entire unit fed by the ventilation system. Clearly, that exposure is not desirable when only atmospheric control at a specific location is required.
Additionally, specific locations remote from the central power source often do not have convenient power sources for driving independent atmospheric control units. Also, it is often desirable that noise levels be kept to a minimum and for that reason independent, power driven units are not entirely satisfactory.
The need for a simple, economical atmospheric control system for use in units having forced air ventilation systems is readily apparent.